Honeycomb structures are configured to meet design requirements for particular structural components, such as used in high temperature and highly stressed environments. As a structural core material, honeycomb structures can be used in different types of aerospace vehicles and supporting equipment. For example, panels formed with an underlying honeycomb structure, as used in the aerospace industry, provide aerospace vehicles and supporting equipment with minimum weight qualities, relatively high heat shielding properties, aerodynamically smooth surfaces, and relatively high fatigue-resistant structural qualities.
In one conventional aerospace industry application, the honeycomb structure is utilized as an underlying structural component of a heat shield. For example, in such an application, the honeycomb structure is formed of a fiberglass reinforced nylon phenolic material filled with AVCOAT insulation, a mid-density, syntactic, silica-phenolic foam material, available from Textron Systems Corp. of Wilmington, Mass. In this application, the fiberglass reinforced nylon phenolic material defines a plurality of individual cells that form the honeycomb cell walls with the AVCOAT insulation residing within each honeycomb cell.
To create the honeycomb structure, an assembler places a layer of raw nylon phenolic material on a table having a series of precisely spaced parallel slots. The assembler then positions a set of metal pins or mandrels over the material and pushes the pins into the slots so that the material conforms to the contours of the table. The pins are formed of a steel or aluminum material having hexagonal cross-sections and are coated with a release agent to facilitate removal of the pins, as described below. Next, the assembler places a second layer of raw nylon phenolic material over the first row of metal pins and disposes a second row of pins over the second layer of material and inserts the second set of pins into the slots formed by the underlying first row of pins. The assembler can then add additional, alternating layers of nylon phenolic material and pins to the base to build the thickness of the overall honeycomb structure to a particular thickness. The assembler then applies pressure and/or heat to the resulting structure in order to consolidate and cure resin matrix carried by the material layers of the structure.
Once the curing process has been completed, the assembler removes the pins from the hardened material layers to provide a honeycomb structure having hexagonally-shaped cells. The assembler then cleans the honeycomb structure, such as by using a plasma cleaning process, to remove contaminants, such as residual mold release agents, from the structure. The assembler then manually fills each cell with AVCOAT insulation, such as AVCOAT 5026-39, using a device similar to a caulking gun. The assembler then manually inspects and X-rays the resulting structure to confirm proper fabrication and to ensure that the AVCOAT insulation has as substantially consistent density within the honeycomb cells.